How do you say I'm at home in Japanese?

Answer 1

if you are a girl then you say: watashi to kyo ni sunde imasu

if you are a boy then replace watashi with boku

Answer 2

お家です。 Ouchidesu.

お家にいます。Ouchini imasu.

内にいるよ。Uchini iruyo.

Three possibilities from very common, to slighly more formal to a confimation spoken to friends.

Answer 3

You may say 'Doko ni sunde imasu ka.'

Answer 4

東京